Mirrorless Camera
An interchangeable-lens camera with no reflex mirror, where the sensor feeds an electronic viewfinder or rear screen directly.
In depth
Removing the mirror box shortens the flange focal distance, which lets designers place the rear element close to the sensor and build simpler, better-corrected wide-angle lenses. It also means focusing happens on the imaging sensor itself, eliminating the front- and back-focus calibration that plagued phase-detect DSLRs, and it allows the finder to show the actual exposure and white balance before the shutter fires.
Examples in practice
A mirrorless body can adapt almost any legacy lens, because its short flange distance leaves room for an adapter of the right thickness.